Die unit for extruding shapes of organic plastic materials



July 309 94@ R. s. JESIUNom/sm 2,405,039

DIE UNIT FOR EXTRUDING SHAPES OF ORGANIC PLASTIC MATERIALS Filed Feb.26, 1944 Eliza :wie eggs Patented July 3o, 194s 2,405,039

UNITED STATES PATENT oFEicE DIE UNIT FOR EXTRUDING SHAPES OF ORGANICPLASTIC MATERIALS Raymond S. J esionowski, Hartford, Conn., assignor toPlax Corporation, Hartford, Conn.. a corporation oi Delaware ApplicationFebruary 26, 1944, Serial No. 524,116

3 Claim. 1 This invention relates to the forming ot shapes by extrusionof organic plastic materials through a die and has particular relationto the extrusion of shapes to be drawn into fiber.

Z ceives hot plastic material therefrom, as explained hereinafter.

The drawing rolls I6, il, I8 and i9 may respectively be mounted onshafts 2 l, 22, 23 and 24,

Fiber of organic plastic material has many 5 driven by Sprockets 253 25,2l and 2.8 by means uses which usually require that the ber is smooth 0fa Cham 29 Whlch, in turn, is driven by one and of uniform gauge Forexemple, ber of of the two sprockets 3l and 32. The chain 29 polystyreneis useful as electrical insulation. 1S dllfen at Such Speed and th?S1295 0f the Ye' But unexpected dimeulty has been experiencedspectivesockets are so proportioned as to cause in attempting to extrudecertain plastic mate-J l0 the Pulling Tous 5 0 rotalte'at thedeslredpeds Hals which may be drawn into ber Such as poly., to draw theplastic material and reduce its size styrene. This dimculty arises whenSuch mate to thesize desired. It will be understood that rials areheated and extruded through a die in rllkllable means may be employedfor drawing the customary way to form-Smau shapes suh 1.- Tlie die unit35 comprises a barrel 36 heat asrodswliichmaybedrawnintofiber. Thedif-fJ. kted 31 Th I 3 l .n' th ilculty is that the material wigglesviolently as auhngass t'he jmelagsolfs it issues from the die andassumes a crinkled or i n a smooth strglght shape .of umform thlcknes 2042 through which pass .bolts one of which is indi- When the crinkledshape is drawn, a ber of velg,7

. cated at 43, screwed into the outer end of the barllneven tmkness or.gauge 1s formed the vana rel 36 and serving to hold the bushing dieplate @ons .m thickness bemg very pronounced' such and retainer ring inassembled relation yas shown. resarcir essere u, The m e of a no e1- dit fl; xtrudin mu sha? 25 turned to conical shape, as indicated at 44, soas a Y, e o ls ghs f peso to direct the plastic material 45 from thescrew 013m@ plast Huitema 'by t e use o Wncn stutter (not shown) intothe central passage 4E wiggling of extruding shapes 1s prevented and awhich runs through he bushing. This passage mooth shape 0f uniformthmkness may be 4G preferably is or substantial diameter approxiormed 3emately as shown.

ther obiects and advantages of the invention on its Outer face; thebushing 3g carries a C0ni will be pointed out in or will be apparent frflm cally shaped projection 4l which is received by, the @umfangSpecification and the accompanying out slightly spaced from a conicallyshaped hole mY/mg 1.11 Wmch h i 48 formed on the inner side of the dieplate 4l,

F13' `1 1S l' Pamal View m 51de eevato@ im 35 thus providing arestricted unobstructed passage eyxtrusmn d1@ uml' emnodymg me Presentmven 49 of conical shape and annular cross section betln and 0f drawmgapparatus for me producties tween the bushing sa and the die niet@ 4i.This 0f pf; I passage 4S is extended at its base through a trans- Flg a1S an enlarged 'we w 1n Yertlal longwdl Verse annular passage into anumber of longinal Sectlon 0f the @Xbruslon d1@ un of El@ 4e tuclinalpassages 52 drilled from the inner side of and. i 1 l l thedie plate 4ithrough the passage 5i tangent F 1g- 3 1S a' VeWn tfansf'rs? s601710?taken 05; to the outer edge a oiT said passage, as shown the line 3-3 ofFig. 2 looking in the direction ol; n Fig 3 my desinee number ofpassages 52 the arrows. e a may be provided, ten of such passages beingIn Phe apparatus 11h15 ated. m me dfa'wm 45 shown equally spaced in acircle concentric to the there is shown at 35 an extrusion die unit emnam of tne die plate M The Outer ends of the bodylng the invention andwhich forms a P915 passages 52 may converge to .form smaller oriof theextrusion apparatus. The rest of such ape nees el, 53, which orificespreferably, have releparatus (which is not shown) comprises a screwtively thin lips as shown., driven by suiiable melius. and Operating in8 50 The outer edge of the ring 42 may be spirally heated cylinder intowhich organic plastic maten grooved as shown at 55 to receive anelectrical rial is fed so that it can be heated, compressed resistance56, which may be wound in the grooves and worked into a substantiallyuniform mass of for the purpose of heating the ring 42, plate 4i, thedesired working viscosity. The die unit 35 and bushing 38, which alsowill be heated by 'the is suitably connected to the screw stuifer andre- 55 barrel 36 from jacket 3l.

The plastic material is so acted upon in the die unit 35 that wigglingof the extruding material .is eliminated and smooth shapes or rods areextruded, such as shown at 58. When such extruded shapes are drawn as bymeans of the drawing rolls I6, I1, I8 and I9, Fig. 1, a smooth ber 59 ofuniform thickness and free of bumps or unevenness is obtained.

The passage 49 preferably is very narrow or restricted, its thicknesspreferably being of the order of slr of an inch. Also it is preferred tomake the passage 52 of substantially greater diameter than the width ofpassage 49. For best results passage 52 should be greater than 1A; inchand preferably about 1A; inch in diameter.

In the use of the novel die unit 35, the plastic material, after beingheated and worked in the screw stuffer (not shown) is further heated inthe die unit as it passes into it, as it iiows through the passage 46(which effects a substantial reduction in the thickness of the plasticmaterial), as it flows in very thin section through the narrow passages49 and 59, and as it ows through the substantially larger passages 52and through the orifices 53.

Such heating, which may be very intense and effective, in conjunctionwith the diameters or thicknesses of the several passages or theirrelative proportions, particularly in conjunction with the relativenarrovmess of passages 49 and 5i, through which the plastic passages inthin cross section, insures that the plastic material can be veryuniformly heated to a condition of low viscosity by the time it reachesorifices 53. This may serve to permit relaxation of orientation orelastic memory particularly of materials which are rubbery when heatedto extrusion temperatures.

rI'he narrowness of the passages 49 and 5I also provides a substantialdrop in pressure between the passages 45 and the passages 52, so thatthe pressure in passage 52 is relatively low. This relatively lowpressure condition in passage 52 may provide the opportunity forrelaxation of orientation in the plastic material passing through thepassages 52 under the effect of the heat transmitted to the materialtherein through the ring 42 and the walls of said passages. Thispressuredrop may also tend to prevent spurting or turbulent flow as the materialissues from oriiices 53.

The relatively large diameter of the passages 52 may result in a slowerrate of flow of the plastic material through said passages than wouldoccur with passages of substantially smaller diametenfor example 1A; ofan inch or less, this aiording suiiicient time for heating andrelaxation of orientation or elastic memory. The relatively large sizeof passages 52 may also tend to prevent spurting or turbulent nowthrough oriiice 55.

The conically shaped passage 49 and the annular passage i areunobstructed and permit even flow and distribution of the plasticmaterial to the passages 52, thus insuring that the plastic materialwill extrude at a uniform rate from all of the orices 53.

It will be understood that the orifices 53 may be of any size desired,that is, may be larger or smaller than shown in Fig. 2. In theproduction of fiber it is preferred to use a relatively small orifice 53in order to reduce the amount of drawing necessary to form ber of smalldiameter.

Various changes may be made in the details of construction and mode ofoperation of the illustrated embodiment without departing from the scopeof the appended claims.

Having thus described my invention what I desire to claim and secure byLetters Patent is:

l. A die unit for the extrusion of small shapes of organic plasticmaterial without crinkling or spiraling comprising a barrel, a bushingassociated with the discharge end of said barrel, a die plate associatedwith said bushing and having formed therein a plurality of longitudinalpassages terminating in extrusion'orifices, means for holding saidbarrel, bushing and die plate in assembled relation, said bushing havinga central passage therethrough, spaced complementary surfaces on saidbushing and in said die plate respectively which surfaces areconstructed and arranged to form an internal, elongated and restrictedpas-` sage of annular cross section for conducting said plastic materialfrom said central passage to the longitudinal passages in said dieplate, and means for heating said die plate.

2. A die unit for the extrusion of small shapes of organic plasticmaterial without crinkling or spiraling comprising a barrel, a bushingassociated with the discharge end of said barrel, a die plate associatedwith said bushing and having formed therein a plurality of longitudinalpassages terminating in extrusion orifices, means for holding saidbarrel, bushing and die plate in assembled relation, said bushing havinga central passage therethrough, spaced complementary surfaces,comprising conical surfaces, on said bushing and in said die plate soconstructed and arranged as to form an internal, elongated andrestricted passage of annular cross-section for conducting said plasticmaterial from said central passage to said longitudinal passages, andmeans for heating said die plate.

3. A die unit for the extrusion of small shapes of organic plasticmaterial without crinkling or spiraling comprising a barrel, a bushingassociated with the discharge end of said barrel, a die plate associatedwith said bushing and having formed therein a plurality of longitudinallpassages of substantial length terminating in extrusion orifices, meansfor holding said barrel, bushing and die plate in assembled relation,said bushing having a central passage therethrough, spaced complementarysurfacesconstructed and arranged to form an elongated restricted passageof annular cross section for conducting-said plastic material from saidcentral passage to said longitudinal passages, said restricted passagehaving a Width substantially less than that of said longitudinalpassages, the width of said restricted passage being of the order ofapproximately one thirty-second of an inch and the width of saidlongitudinal passages being of the order of approximately one-quarter ofan inch, and means for heating said die plate to heat the plasticmaterial in said destricted passage and in said longitudinal passages.

RAYMOND S. JESIONOWSKI.

